Magnetic resonance system and method

• US 7,868,614 B2
• Filed: 01/16/2007
• Issued: 01/11/2011
• Est. Priority Date: 01/16/2006
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Bito, Yoshitaka, Ochi, Hisaaki
• Primary Examiner(s): Koval; Melissa J
• Assistant Examiner(s): Vargas; Dixomara
• Application Number:
  US11/623,418
• Publication Number:
  US 20070164742A1
• Time in Patent Office: 1,456 Days
• Field of Search: 324300-322
• US Class Current: 324/307
• CPC Class Codes: G01R 33/34046 Volume type coils, e.g. bird-cage coils; Quadrature bird-cage coils; Circularly polarised coils
• CPC Class Codes: G01R 33/3415 comprising arrays of sub-coils , i.e. phased-array coils with flexible receiver channels

Abstract

The invention provides a magnetic resonance system and method of measuring continuous regions at high speed without decreasing SN. As a receive system, multiple RF coil sets a, b comprising multiple RF coils a1, a2, b1, b2 are disposed in positions where there is no spatial interference with at least one of the RF coils of an adjacent coil set, the RF coils constituting each coil set are changed over one by one, sets of RF coils which do not interfere mutually are activated, and signals are simultaneously acquired from a number of regions equivalent to the number n of coil sets. Hence, if the number of coil sets is set to n, the measurement time can be shortened to 1/n. Alternatively, the SN can be improved by √n times.

Claims

1. A magnetic resonance system, comprising a static magnetic field generation system, an RF transmitter which transmits a nuclear magnetic signal to an object placed in the static magnetic field, an RF receiver which receives a nuclear magnetic resonance signal from said object, and a signal processing system which generates an image and/or spectrum of said object using the nuclear magnetic resonance signal received by said RF receiver, wherein:

said RF receiver comprises multiple receive units and at least one array of multiple coils which overlap without forming any gaps therebetween, and the multiple coils are grouped into multiple coil sets connected to each of said multiple receive units, and wherein;

each coil set comprises multiple RF coils and is disposed in a position which does not spatially interfere with at least one RF coil of the respectively adjacent coil sets of said multiple RF coils, and further comprises a switch controller which controls ON-OFF of said RF coils to sequentially switch one of the multiple RF coils forming each coil set to ON, a coil switch which selectively connects one of said multiple RF coils to said receive unit, and a coil controller which controls said switch controller and said coil switch.

2. The magnetic resonance system according to claim 1, wherein:

said RF transmitter comprises at least one RF transmit unit; and

said RF coils of said multiple coil sets of said RF receiver are switchable to also function as transmitting coils of said RF transmitter, and are provided with a transmit/receive switches which switch said RF coils between the receive unit and the transmit unit.

3. The magnetic resonance system according to claim 2, wherein the multiple coil sets are connected to the same transmit unit.

4. The magnetic resonance system according to claim 1, wherein:

said RF transmitter comprises at least one transmit unit and multiple coil sets, and wherein;

each coil set comprises multiple RF coils and is disposed in a position which does not interfere with at least one RF coil of the adjacent coil sets, and further comprises a switch controller which controls ON-OFF of said RF coils to sequentially switch one of the multiple RF coils forming each coil set, a coil switch which selectively switches each of said multiple RF coils between the transmit unit and the receive unit, and a coil controller which controls said switch controller and said coil switch.

5. The magnetic resonance system according to claim 4, wherein the multiple coil sets are connected to the same transmit unit.

6. The magnetic resonance system according to claim 1, wherein said RF transmitter comprises an RF coil covering sensitivity map regions of two or more coil sets.

7. The magnetic resonance system according to claim 6, wherein part of the sensitivity map regions of multiple RF coils constituting said coil set mutually overlap.

8. The magnetic resonance system according to claim 1, wherein said multiple RF coils are arranged in an uniaxial direction.

9. The magnetic resonance system according to claim 1, wherein said signal processing system is provided with a correction method which corrects a sensitivity distortion of the nuclear magnetic resonance signal received by the multiple RF coils.

10. The magnetic resonance system according to claim 1, provided with a moving device which moves said object in a static magnetic field, and wherein:

said multiple coil sets are disposed in the motion direction of the object moved by said moving device.

11. A magnetic resonance measurement method comprising which transmitting an RF field to an object placed in a static magnetic field, receiving a nuclear magnetic resonance signal from said object, and generating an image and/or a spectrum of the object using said nuclear magnetic resonance signal received by an RF receiver having multiple receive units and at least one array of multiple coils which overlap without forming any gaps therebetween, and the multiple coils are grouped into multiple coil sets connected to each of said multiple receive units, and each coil set comprises multiple RF coils, said method repeatedly performing:

a step of transmitting an RF field to the object; and

a step of switching one RF coil of each multiple coil set to receive a nuclear magnetic resonance signal, and sequentially changing over the RF coil of each coil set switched to receive the nuclear resonance signal, and generating an image and/or a spectrum of the object using the nuclear magnetic resonance signal sequentially received by the multiple RF coils.

12. The magnetic resonance measurement method according to claim 11, wherein said method further comprises a step of switching over the RF coil from transmitting to receiving after transmission of the RF field.

13. The magnetic resonance measurement method according to claim 11, wherein said coil sets are arranged in a uniaxial direction;

and

the step of transmitting said RF field includes generation of the RF field having an excitation profile which excites multiple cross-sections perpendicular to the array direction of said coil sets.

14. The magnetic resonance measurement method according to claim 13, wherein said RF field is a pulse waveform obtained by performing an inverse Fourier transform of a desired excitation profile, or a DANTE pulse.

15. The magnetic resonance measurement method according to claim 13, comprising a step which, when the step of transmitting said RF field and the step of receiving said nuclear magnetic resonance signals are repeated, during moving of said object in the direction of said coil sets.

16. The magnetic resonance measurement method according to claim 15, wherein, in the step of moving of said object, said object is moved by a width shorter than the interval of the coil sets.

17. The magnetic resonance measurement method according to claim 11, wherein said coil sets are arranged in a uniaxial direction, and the step of transmitting said RF field generates an RF field having an excitation profile which excites multiple cross-sections parallel to the array direction of said coil sets.

18. The magnetic resonance measurement method according to claim 17, wherein the pulse shape of said RF field is a sinc function.

19. The magnetic resonance measurement method according to claim 11, comprising a step which generates a spectroscopic image using a nuclear magnetic resonance signal received by multiple RF coils of each coil set.